From c68809400f149d3f176e03a3ab36e576a4d5ae79 Mon Sep 17 00:00:00 2001
From: popcornmix <popcornmix@gmail.com>
Date: Wed, 18 Jun 2014 13:42:01 +0100
Subject: [PATCH] vmstat: Workaround for issue where dirty page count goes
 negative

See:
https://github.com/raspberrypi/linux/issues/617
http://www.spinics.net/lists/linux-mm/msg72236.html
---
 include/linux/vmstat.h | 4 ++++
 1 file changed, 4 insertions(+)

--- a/include/linux/vmstat.h
+++ b/include/linux/vmstat.h
@@ -219,7 +219,11 @@ static inline void __inc_zone_state(stru
 static inline void __dec_zone_state(struct zone *zone, enum zone_stat_item item)
 {
 	atomic_long_dec(&zone->vm_stat[item]);
+	if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&zone->vm_stat[item]) < 0))
+		atomic_long_set(&zone->vm_stat[item], 0);
 	atomic_long_dec(&vm_stat[item]);
+	if (item == NR_FILE_DIRTY && unlikely(atomic_long_read(&vm_stat[item]) < 0))
+		atomic_long_set(&vm_stat[item], 0);
 }
 
 static inline void __inc_zone_page_state(struct page *page,
